Swing feel gives your guitar playing a very nice bouncing effect. All the great musicians, flatpickers included, apply swing feel to a lot of songs, solos, etc. Fiddle tunes sound great with a little bit of swing feel.

There are two "feels" in music: straight feel, where eighth notes are evenly paced as they appear on written music, and swing feel, where eighth notes are played with an underlying triplet feel. It's important to be aware of the difference and to apply one or the other feel according to the tune you are playing.